Fish diseases and injuries are not only detrimental to the physiological well being of live fish, but also can adversely affect the physical appearance of otherwise viable fish. The prevention, control and treatment of fish diseases and fish injuries is particularly important for fish that are kept in artificial or confined environments such as aquariums or ponds, such as ornamental ponds or aquaculture ponds.
Fish that are netted, handled or otherwise placed in stressful situations, e.g., under low oxygen, high carbon dioxide, contaminated water or fluctuating temperature conditions, become more vulnerable to disease, such as those of bacterial or fungal origin. When fish are transported in high concentrations and/or in small volumes of water, they are often subject to trauma or injury such as being scraped, lacerated, bitten and otherwise wounded. Such shipping conditions may also expose fish to contaminated water, e.g., from natural waste products of fish and from decaying food and dead fish. Contaminated water is also an environment favoring the growth of pathogens that cause fish diseases.
The term "fish diseases" and other similar terms as used herein are intended to cover not only fish diseases of bacterial or fungal origin, but also fish suffering from, damaged by, or afflicted with trauma or injuries such as wounds, e.g., lacerations, tears and bites, as well as scrapes, abrasions, burns or the like. Rapid healing of such injuries is often slowed, delayed or precluded by the presence of pathogenic microorganisms in the water environment harboring the fish or in the injured skin, tissue or other like part of the fish.
Fish disease therapies that avoid the use of potent drugs or chemicals with adverse side effects or that avoid the necessity for precise dosing requirements are desirable for fish in confined environments. While isolation and treatment only of the specific diseased or injured fish is preferred, as a practical matter, such isolated treatment is not often possible, resulting also in exposure of healthy fish to the treatment. Consequently, treatment of individual diseased fish usually entails exposure of healthy fish and all other beneficial organisms in the environment to the active ingredient as well. For this reason, therapeutic treatments for diseased fish that utilize naturally derived substances which are not injurious to other aquatic animals or plants also present in the water are particularly preferred.
The treatment of damaged fish tissue in living fish with aloe vera is described by Goldstein in U.S. Pat. No. 4,500,510, assigned to the assignee of the present invention. The prevention and treatment of bacterial diseases in fish with eucalyptus extract is described in Japanese Patent Publication 04-360839. Eucalyptus extract is a complex mixture obtainable from leaves of Eucalyptus species trees, and the primary component of eucalyptus oil is 1,8-cineole, sometimes also called eucalyptol (about 70-85%).
The present invention is based on the unexpected discovery that cajeput is highly efficacious in the therapeutic treatment of fish and other aquatic animals. Cajeput oil, obtainable from leaves of the tree Melaleuca cajuputi, M. leucadendron and other species of Melaleuca (Myrtaceae) contains a large number of components, most of which are terpenoids and one major component being 1,8-cineole (about 39%). Although cajeput oil is known for its therapeutic properties in treating humans (see, e.g., Cuong et al., "Antibacterial Properties of Vietnamese Cajuput Oil," J. Essent. Oil. Res., 6, pp. 63-67 (January 1994)), its use in treating fish has not previously been reported or suggested.